Manufacturing leather substitute



Patented May 5, 1953 UNITED STATES PATENT OFFICE No Drawing. Application September 16, 1949, Se-

rial No. 116,225. In Italy November 25, 1948 1 Claim.

This invention relates to a novel article of manufacture which is adapted to substitute leather in its various uses and is composed of rubber admixed with textile fibres cut to very short length. The best results are obtained by using cotton fibre.

The method of manufacture is as follows.

The rubber is ground as usual in the mixer. As soon as a sheet, which may even not be continuous, is formed on the front cylinder, accelerators, pigments or dyes and the finely comminuted vegetable fibres are incorporated therewith after having submitted them to a dyeing bath with aniline dyes and successively dried in an oven.

After coarse mixing, the mixture is fed through narrowly clamped cylinder of a refining machine. this operation being repeated several times, till a satisfactory homogenous sheet is obtained.

The mixture is then returned to the mixer and admixed with the remaining fillers, as zinc white, carbon black, kaolin, talc, etc. whereupon the vulcanizer is added.

The cylinders are kept cool during the above operations.

The resulting mixture may be drawn to the desired thickness on the cylinders of the mixer, if intended to be pressed. If the mixture is to be transformed into calendered sheets, it is first admixed with considerable quantities of plasticisers adapted to be vulcanised. The rolls of the calender shall be likewise kept cool.

Vulcanisation in the press or in an autoclave is carried out by the usual methods at low temperatures and over longer periods.

Upon completion of vulcanisation, the pressed or calendered products may be polished in order to confer a chamois leather aspect to the surfaces of the articles.

Example A mixture is first formed in the above described manner, of approximately the following composition by weight in per cent:

Smoke sheets 48.00 Colored fibres 32.00 Stearic acid 0.45 Zinc oxide- 4.00 Ventilated sulphur 1.50 Tetraethylthiuram disulfide 0.15 Mercaptobenzothiazol dlsulfide 0.55 Mineral oil 1.50 Phenylbetanaphthylamine 0.45 Carbon black 11.50

The above mix is vulcanised. in moulds under a press at the temperature of about 125 C. during about 15 minutes at a pressure of about 50 lag/sq. centimeter. A product of the black chamois type is obtained, which may usefully be employed in, all cases in which black chamois leather is usually employed.

Samples of this product submitted to tests have given the following results:

Abrasion index (over 1000 meter path under a pressure of kg. 6,200) millimeters 0.2 Tensile stress kg./sq. centimeter 61 Residual track (after 50 minutes under a load of kg./sq. centimeter) millimeters 0.14

Waterproofness-No cracking or breakage after 15 minutes tests on test samples subjected to an hydraulic pressure of 4 atmospheres without supporting crate, pressure unaltered.

What I claim is:

Method of manufacturing a leather substitute of the chamois type, consisting in forming a mix of approximately the following composition by Weight per cent:

Smoked sheets 18.00 Colored fibres 32.00 Stearic acid 0.15 Zinc oxide 4.00 Ventilated sulphur 1.50 Tetraethylthiuram disulfide 0.15 Mercaptobenzothiazol disulfide 0.55 Mineral oil 1.50 Phenylbetanaphthylamine 0.45 Carbon black 11.50

and in vulcanizing said mix in molds under a press at a temperature of about C. during about 15 minutes at a pressure of about 50 kg. 'sq. centimeter.

LUCIANO VALENTINI.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,326,681 Matthaei Dec. 30, 1919 1,928,356 Haertel Sept. 26, 1933 2,013,553 Day Sept. 3, 1935 2,039,529 Guinzburg May 5, 1936 2,180,906 Maywald Nov. 21, 1939 2,273,206 Kuhn Feb. 17, 1942 OTHER REFERENCES Pearson's Crude Rubber and Compounding Ingredients," third edition, New York, 1918, pages 356-357. 

